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Tea is one of the worlds most popular and widely consumed beverages. It is a common pastime to enjoy a cup of tea in the sunshine. However, little attention has been given to understanding the possible photochemical reactions occurring beneath the calm surface of brewed tea. Epigallocatechin gallate (EGCG), which is widely used in food and beverages, is the most significant active ingredient found in tea. In this study, we investigated the presence of free radicals in both an aqueous EGCG solution and brewed tea under simulated sunlight conditions. To our surprise, we unexpectedly observed the production of hydroxyl radicals (•OH) in brewed tea. It was found that sunlight irradiation played a critical role in the formation of •OH, independent of the presence of metal ions. Furthermore, we demonstrated that the •OH generated from the EGCG aqueous solution induced cell cytotoxicity and DNA damage in vitro. Considering the crucial role of •OH in various fields, including human health and the environment, it is important to further explore the practical implications of •OH production in brewed tea under sunlight. In summary, our study unveils the unexpected formation of •OH in brewed tea and emphasizes the significance of sunlight-induced reactions. The observed cytotoxic and DNA-damaging effects of •OH emphasize the importance of understanding the potential health consequences associated with tea consumption. Further research in this area will contribute to a better understanding of the broader implications of •OH production in brewed tea under sunlight.

Bismuth sulfide (Bi2S3) single crystal shows a great advantage of the direct band gap, high photo‐absorption, and non‐toxic elements. The ideal prerequisites for ultrasensitive photodetector is low noise and high gain, which are however not simultaneously present in existing Bi2S3 photodetectors. Herein, a three‐terminal phototransistor based on Bi2S3 flakes, achieving both low noise and high photo‐gain for ultrasensitive photodetection capability is developed. By applying negative gate voltage, the Bi2S3 channel is depleted, leading to a low noise spectral density of 3.3 × 10−12 A Hz−1/2. Leveraging the photo‐gating effect, a high photo‐gain of ≈108 is also yielded. These two factors have led to a high responsivity of 3 × 108 A/W and high detectivity up to 1.6 × 1015 Jones at 635 nm, which have surpassed that in commercial and newly emerging photodetectors. Through the temperature‐dependent electrical transport and photo‐response measurement, the phototransistor demonstrates an interesting metal‐semiconductor transition due to the strong electron‐electron interactions by applying positive gate voltage for high levels of electron doping. A suppressed hysteresis and persistent photoconductivity are observed at low temperatures, suggestive of the existence of trap states. This work develops the Bi2S3 photo‐transistor with ultrasensitive photodetection and metal‐semiconductor transition, providing a promising system for strong correlation effects and photodetector applications. [ABSTRACT FROM AUTHOR]

Photodetectors based on two-dimensional (2D) materials have demonstrated their advantages of low-cost, high-performance, small-size, flexibility and large-scale manufacture. In this work, 2D MoS2-based photovoltaic detectors with a switchable mode have been achieved through a Schottky and lateral PN homojunction. By applying different bias voltages, the photodetection mode can be switched between the photodiode and photoconductor, combining the advantageous features of both modes in one device. In the photodiode mode, a significant rectifying and photovoltaic behavior can be achieved and tuned by the gate voltages, achieving a fast photo-response speed of ∼10 ms. In the photoconductor mode, the photoconductive effect can lead to a photo-gain mechanism, a high responsivity up to 103 A W−1 and a high detectivity of 4.1 × 1012 Jones in the Schottky device. This work develops a MoS2 photodetector based on a Schottky and PN homojunction using a facile method, and the switchable operation mode endows our device with the capability of customized photodetection applications for different needs. [ABSTRACT FROM AUTHOR]

Emerging tribovoltaic nanogenerator (TVNG) technology, which can capture mechanical energy at dynamic semiconductor interfaces and generate instant direct current (DC) outputs, is considered promising to mitigate growing energy demand. However, the unsatisfactory charge excitation and extraction efficiency limit its electrical output stability and even practicability. Here, a novel strategy is proposed to synergistically modulate charge generation and transfer dynamics by integrating ferroelectric and photovoltaic effect with tribovoltaic effect, and thus a multi‐effect coupled Schottky TVNGs is, for the first time, developed. Research indicates that such coupling mechanism involving ferroelectric polarization, photoexcitation, and triboelectricity can allow TVNGs to jointly collect light and mechanical energy to excite more charges, and meanwhile, incorporation of strong electric fields can also be induced by controlled polarization to assist Schottky junction in modulating separation/extraction efficiencies of these charges. Ultimately, this multi‐effect coupled devices deliver impressive DC output of 7.3 V and 69.8 µA, outperforming similar coupled Schottky junction TVNGs. Besides that, its feasibility for multifunctional sensing and photodetection is also demonstrated. This study proposes an effective strategy for modulating performance while extending its functionality, which can expedite the development and potential application of advanced TVNGs. [ABSTRACT FROM AUTHOR]

For the need of direct contact with the skin, electronic skins (E‐skins) should not only fulfill electric functions, but also ensure comfort during wearing, including permeability, waterproofness, and easy removal. Herein, the study has developed a self‐adhesive, detach‐on‐demand, breathable, and waterproof E‐skin (PDSC) for motion sensing and wearable comfort by electrospinning styrene‐isoprene block copolymer rubber with carbon black nanosheets as the sensing layer and liner copolymers of N, N‐dimethylacrylamide, n‐octadecyl acrylate and lauryl methacrylate as the adhesive layer. The high elasticity and microfiber network structure endow the PDSC with good sensitivity and high linearity for strain sensing. The hydrophobic and crystallizable adhesive layer ensures robust, waterproof, and detaching‐on‐demand skin adhesion. Meanwhile, the fiber structure enables the PDSC good air and water permeability. The integration of electric and wearable functions endows the PDSC with great potential for motion sensing during human activities as both the sensing and wearable performances. [ABSTRACT FROM AUTHOR]

Semiconducting two-dimensional (2D) MoS2 has emerged as a promising material for logic transistors and photodetectors, benefiting from its considerable mobility and strong light–mater interaction, along with the low cost and large area growth. However, the reported MoS2 based photodiode and photoconductor suffer from either absence of gain or slow dynamic response, limiting their practical application with high sensitivity. Herein, the lateral bipolar junction photo-transistors (BJPT) with both PNP and NPN architectures are fabricated by partial chemical doping, which combine the advantages of both photodiode and photoconductor by producing a high photo-gain of ∼103 electrons per photon adsorption due to the carrier amplification and remaining a well dynamic response with speed less than 10 ms. In this device, we achieve a high responsivity of 2 × 103 A/W and high sensitivity with specific D* up to 7.2 × 1011 Jones at 635 nm in the amplification region. This work demonstrates a BJPT device scheme that can combine both high gain and fast temporal response in a single device, promoting the wide applications of 2D ultra-thin photodetectors. [ABSTRACT FROM AUTHOR]

The rapid advancement of modern computing technology has pushed complementary metal–oxide–semiconductor (CMOS) scaling to its limits, driving the need for alternative approaches such as in-memory computing. Memtransistors have emerged as promising candidates for in-memory computing, offering the integration of data memory and processing within a single device. In this study, our device exhibits optoelectronic switching behavior, allowing for laser pulse-induced memory and voltage pulse-induced erasing, enabling access to optical storage and switching properties. A laser pulse can induce a persistent resistance state that remains stable for extended duration surpassing 4 × 103 seconds. Furthermore, the memtransistor exhibits a high memory on/off ratio of approximately 2 × 103 and fast light writing time (2 ms) and voltage erasing time (2.48 ms). The demonstrated ZnO/WSe2 mixed-dimensional heterostructure memory device represents a significant advancement in optoelectronic in-memory computing. [ABSTRACT FROM AUTHOR]

Highly efficient nano piezoelectric devices and nanomedical sensors are in great demand for high-performance piezoelectric materials. In this work, we propose new asymmetric XMoGeY2 (X = S, Se, Te; Y = N, P, As) monolayers with excellent piezoelectric properties, dynamic stability and flexible elastic properties. The piezoelectric coefficients (d11) of XMoGeY2 monolayers range from 2.92 to 8.19 pm V−1. Among them, TeMoGeAs2 exhibits the highest piezoelectric coefficient (d11 = 8.19 pm V−1), which is 2.2 times higher than that of common 2D piezoelectric materials such as 2H-MoS2 (d11 = 3.73 pm V−1). Furthermore, all XMoGeY2 monolayers demonstrate flexible elastic properties ranging from 96.23 to 253.70 N m−1. Notably, TeMoGeAs2 has a Young's modulus of 96.23 N m−1, which is only one-third of that of graphene (336 N m−1). The significant piezoelectric coefficients of XMoGeY2 monolayers can be attributed to their asymmetric structures and flexible elastic properties. This study provides valuable insights into the potential applications of XMoGeY2 monolayers in nano piezoelectric devices and nanomedical sensors. [ABSTRACT FROM AUTHOR]

The interfacial design of the electronic skins (E‐skins), which are increasingly crucial in areas like exercise monitoring, healthcare, etc., has a great impact on wearability and functions. The adhesion between E‐skin and human skin serves as the foundation for various functionalities. In addition to robust adhesion strength, detaching‐on‐demand, and waterproof abilities are also important for long‐time wearing and comfort detachment after use. Here, self‐adhesive, detach‐on‐demand, and waterproof hydrophobic E‐skins (PBIA) by copolymerization of acrylates with conductive ionic liquid and adhesive components as the strain sensor and triboelectric nanogenerator (TENG) is developed. The strong van der Waals self‐adhesion (shear adhesion of ≈574 kPa, peeling adhesion of ≈110 N m−1), and waterproof abilities under immersing, flushing, and penetrating situations enable the E‐skin to realize stable and long‐time monitoring for body motions in both the resistance sensing and TENG modes. Meanwhile, the easy detach‐on‐demand ability of van der Waals adhesion (574 to 35 kPa and 110 to 7 N m−1) guarantees the easy and comfortable detachment of PBIA after use, avoiding pain or injury to the skin. The adhesion strategy of PBIA can be expanded to other kinds of E‐skins and accelerate the pace of practical applications of E‐skins. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) bismuth triiodide (BiI3) has been emerging as a potential layered material for optoelectronic applications due to its air stability and high atomic density. Although much effort has been devoted to improvements of carrier mobility, conductivity and photoelectric response, performance is still very limited. Here, we report a simple and scalable strategy for greatly improving the electrical and optical properties of 2D BiI3 through high-Îş dielectric engineering. Upon covering with a high-Îş dielectric oxide (Al2O3), air isolation and dielectric screening effects can lead to the reduction of the contact barrier, passivation of trap states, and suppression of Coulomb scattering. As a result, BiI3-based phototransistors can increase carrier mobility by three orders of magnitude and improve photoresponsivity by three orders of magnitude up to 8.05 Ă— 103 A Wâˆ'1. This work develops a new 2D BiI3 material and efficient dielectric engineering for improving mobility and photoelectrical performance, expanding the family of 2D materials and offering a promising strategy for potential nano-device applications. [ABSTRACT FROM AUTHOR]